I participated in the 2016 GB on t4r.org. Order placed in November, received rack in May 2017. It's a great rack, but if I had to do it again, I would have looked deeper at other more flexible options such as the Front Runner with the track system.
I got this figured out. I ordered mine with the Cut out and the piece to take on and off. The piece when putting It has to go down through the cut out and then brought back up and put in place. The safety feature is so the cut out piece won’t fly off if the operator fails to secure It.